The invention relates to permanent magnet electric motors and more particularly, to a flux path of the motor in the form of a coil spring structure to hold the permanent magnets with respect to a frame.
Conventional permanent magnet electric motors include a steel frame carrying permanent magnets and an iron flux ring disposed about the frame or magnets. This structure includes large cylindrical surfaces that typically resonate unwanted noise. Typically, the magnets are bonded or clipped to a steel structure which results in increased assembly costs, additional parts, and added scrap.
Accordingly, there is a need to provide a low-cost frame and flux path structure that holds the permanent magnets, has a reduced parts count, and results in a lower natural frequency to reduce noise.
An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is obtained by providing an electric motor having an armature including windings, the armature being constructed and arranged to rotate a shaft; a commutator; brushes to engage the commutator and conduct electrical current to the windings; permanent magnet structure disposed about the armature; a frame assembly carrying the permanent magnet structure; and a coil spring structure, containing iron, disposed about at least a portion of the permanent magnet structure contacting the permanent magnet structure to define a flux path of the motor.
In accordance with another aspect of the invention, a flux path structure is provided for an electric motor, the motor having a frame and permanent magnet structure. The flux path structure includes a coil spring structure containing iron and disposed about and contacting the permanent magnet structure to define a flux path of the motor.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.